Cathode and method of making same



Oct. 22, 1940. EBE 2,219,217

CATHODE AND METHOD OF MAKING SAME Filed Oct. 27, 1936 INVENTOR. 7 5g. v CD. 7354- ATTORNEY.

Patented Oct. 22, 1940 PATENT orries CATHODE AND METHOD or MAKING SAME John D. Beebe, Detroit, Mich, assignor, by memo assignments, to The Trumbull Metal Products C pa y, a corporation of Delaware, Edward B. Busby, Detroit, Mich, as trustee Application October 2'7, 1936, Serial No. 107,911

3 Claims.

This invention relates to the making of metallic openwork, such as screen, and has for its object to provide an improved method of manufacturing cathodes by which screen can be made in an electrolytic bath.

Many attempts have been made to provide a permanent cathode in the likeness of fine screen upon which metal may be deposited. Much difficulty has been experienced in preserving the cathode surface in perfect condition even when the cathode is made out of the best and most expensive materials and even though initial accuracy has been carried to a high degree of perfection as by the expensive process of etching the cathode surface according to the dictates of a photographic film. It is an object of this invention to teach an economical method of making cathodes which may be used a few times and which are made from a material all of which can be salvaged for making a new cathode.

More particularly it is an object of this inven tion to provide a cathode die and to employ this die in the manufacture of cathodes of a soft metal or alloy which can be made rapidly and accurately and which can be remelted and re-cast in the die as quickly as they show any sign of imperfection.

The invention will be better understood with respect to the accompanying drawing wherein my invention is illustrated and in which Figure l is a perspective view of base plate and a die blank,

Figure 2 is a fragmentary view of the plate and die blank of Figure 1 in the process of being cut,

Figure 3 is a fragmentary view of one corner of 3:; the plate after being cut in one direction,

Figure 4 is a View similar to Figure 3 showing preparation for cutting in the other direction,

Figure 5 is a View similar to Figure 3 after the cuts have been made in both directions,

Figure 6 is a vertical section showing the die in use.

Figure '7 is a partial view of the finished cathode.

More particularly I indicates a plate made of any suitable metal to constitute a support for a second plate 2 of some suitable metal such as steel, the plate 2 being slightly smaller than the plate I for purposes hereinafter described.

Obviously the plates I and 2 may be integral, if 50 more convenient.

In order to manufacture a die from which a cathode may be struck, I provide a multiplicity of small saws 3 fixed on a rotatable shaft 4, the saws being equally spaced from each other by means of the spacers 5. During rapid rotation of these saws the plate 2 is fed therebeneath whereby each saw cuts a shallow groove 6 parallel to the grooves cut by the other saws. The grooves t are then filled with some soft metal I I such as tin and the plate 2 and its base Iare then turned at right angles to the original direction of feed and grooves l are then cut by-again feeding the plate 2 beneath the saws 3. The soft metal II in the grooves 6 acts as a brace for the small projections formed by the second out. After the cuts have been completed the tin may be melted out or it may be removed by an acid wash.

The illustrations in Figures 2, 3 and 4 are greatly exaggerated in the drawing as these grooves need be only a few thousandths of an inch in depth.

Upon the formation of the two-way grooves,

whereby a multiplicity of small projections 9 of equal size and rectangular in cross-section are formed, these projections have sharp corners un- H suitable for striking a die therefrom and I, therefore, recommend that the plate then be washed or immersed in an acid, such as a dilute solution of sulphuric acid, for the purpose of rounding these sharp edges. After this operation I then provide a railing or container walls 8 to form an enclosure around the projections. This enclosure formed from the rails 8 may then be filled with soft molten metal I0 which will take the impression of the grooves and projections of the plate 2. Upon solidification this soft metal blank may be removed. As an example of a suitable soft metal I recommend a mixture of equal parts of lead, tin, bismuth and antimony.

This soft metal blank is, in fact, a negative of the hard metal die and constitutes a cathode blank. This blank is then immersed in molten wax I2 and subjected to a polishing whereby the wax is removed to the point where the small metallic strands in counterpart of the grooves 6 and I become visible. This completes the formation of the cathode which is then electrically connected to a ground and immersed in an electrolytic bath for the deposition thereon of a suitable metalsuch as nickel, copper or the like. The deposition will occur only on the exposed metal and hence forms a screen.

The cathodes as above formed will have a life which is comparatively short as compared to the life of a cathode composed of steel or other hard metal. However, the die illustrated in Figures 1 to 4 will have an indefinite life from which a vast number of cathode blanks may be struck. Thus when the cathodes show signs of deterioration they are merely melted and used again to form a new cathode with practically no waste of material,

In this way it becomes possible to manufacture cathodes rapidly and economically and thus insure the availability of a perfect cathode at all times. I have found that it is possible to make cathodes sufiiciently fine that screen of one hundred and ten mesh may be made therefrom. For fine mesh of this order the grooves 6 and I need be only about five thousandths of an inch thick.

What I claim is:

1. The method of making a cathode which consists in cutting a multiplicity of narrow parallel grooves in the surface of a hard metallic body, in cutting a multiplicity of narrow parallel grooves in said surface normal to the first named grooves thereby forming a multiplicity of small projections, in pouring over said projections and allowing to solidify thereon a quantity of soft metal thereby forming a cathode blank having a multiplicity of small depressions in one surface thereof, in removing said cathode blank from said hard metallic body, and in filling said depressions with a non-conductive material.

2. The method of making a cathode which consists in cutting a multiplicity of narrow grooves in a hard metallic surface, in filling said grooves with a soft metal, in cutting a multiplicity of narrow grooves in said surface normal to the first named grooves thereby forming a multiplicity of small projections, in then removing said soft metal, in pouring over said projections and allowing to solidify thereon a quantity of soft metal thereby forming a cathode blank having a multiplicity of small depressions in one surface thereof, in then removing said cathode blank, and in filling said depressions with a non-conductive material.

- 3. The method of making a cathode which consists in cutting a multiplicity of narrow grooves in a hard metallic surface, in filling said grooves with soft metal, in cutting a multiplicity of narrow grooves in said surface normal to the first named grooves thereby forming a multiplicity of small projections, in then bathing the cut surface in acid whereby said soft metal is removed and whereby the sharp edges of said projections become rounded, in pouring over said projections and allowing to solidify thereon a quantity of soft metal thereby forming a cathode blank having a multiplicity of small depressions in one surface thereof, in then removing said cathode blank, and in filling said depressions with a non-conductive material.

JOHN D. BEEBE. 

